Just a few hours after John McCain endorsed Mitt Romney's candidacy in New Hampshire, a pro-Newt Gingrich PAC, Winning Our Future, has brought up bad memories of the none-too-friendly relationship between the former rivals in 2008.

Earlier today, all old attack ads from McCain and Romney's YouTube pages disappeared. But one, an old web ad entitled "A Tale of Two Mitts," is still available online, and it is now on the front page of Winning Our Future's website.

Why does this ad exist? Because in 2008, Romney and McCain battled it out for the nomination, and McCain often attacked Romney for flip-flopping. This is further proof that Gingrich intends to run a nasty campaign against Romney).

The ad uses Mitt Romney's changing positions on abortion, gun rights, and conservatism against him. It ends with the text, "Mitt Romney's Flip Flops Truly Are Masterpieces," before McCain's approval of the ad.